The present invention relates to computer controlled, automated power saws. Specifically those saws used in the manufacture of engineered wood roof and floor trusses. Truss components of this type require a wide variety of lengths and angle cuts. The criteria for a successful saw in today""s market would have to include but not be limited to, safety, speed, accuracy, durability and low operator cost.
#5,365,812 Harden, Charles Nov. 22, 1994
#5,176,060 Thornton, Jack L. Jan. 5, 1993
#4,454,794 Thornton, Jack L. Jun. 19, 1984
#4,036,093 Thorsell, Roland H. Jul. 19, 1977
#3,910,142 Jureit, John C. Oct. 7, 1975
There are several saws available to truss builders today. Some manual and some computer controlled. The driving force in innovation is to increase production and accuracy as well as decrease labor cost.
An example is that of Harden, U.S. Pat. No. 5,365,812. Harden discloses a saw pivoting on a centerline but moving in a horizontal cutting motion requiring excessive movement to complete a cut. The saw is also unable to angulate until fully retracted. The lumber cannot be cut on both ends without the operator manually rotating it horizontally and inserting it back into the saw. The Harden saw is computer controlled but requires repetitive operator input to initiate successive functions.
The Thornton Saw U.S. Pat. No. 5,176,060 is a two blade saw with no computer control. All angles and work piece lengths are set manually. The machine is efficient at making repetitive cuts producing identical pieces but slow manual setup time makes it impractical. The previous Thornton Saw U.S. Pat. No. 4,454,794 is a similar machine although it is a single blade saw. It is also manually set with the same limitations as the two blade saw.
The Thorsell Machine U.S. Pat. No. 4,036,093 cuts in a vertical motion although operated by means of electric motors and a lead screws which are prone towards fouling with saw dust. The structure of the saw frame is not designed to eliminate lateral deflection at the saw blade making it difficult to ensure accuracy.
The Jureit Saw U.S. Pat. No. 3,910,142 is very similar to the Harden machine referred to earlier. This saw operates in the same manner although was not able to make use of the current PC technology. The Jureit Saw also requires excessive operator input.
The Invention discloses an automated saw apparatus for cutting the component pieces for roof trusses. The apparatus comprises a circular power saw, a processing line whereon stock lumber is conveyed to and from the saw, a waste bin for receiving scrap pieces cut by and discarded from the saw, a control computer and software, and sensors for measuring the lumber as it is conveyed to the saw for allowing the computer to determine how long a board to cut, and where and at what angles to make the cuts.
Accordingly several objects and advantages are as follows, the truss component saw herein described automatically stores, interpolates and displays to the operator data necessary to perform the task of cutting truss component members. As truss component members are by necessity comprised of many different lengths as well as various angle configurations it is necessary that the machine be tractable in its movement as well as conservative of its motion.
An object of the present invention is to perform multiple functions with one apparatus as in the feed conveyors. The feed rollers convey the lumber in and out of the saw as well as measure, position and hold the wood in place as the cut is made.
Another object is to make efficient use of readily available cutting data from the truss engineering program without time consuming operator input.
This is accomplished by using the computer to select the order of cut and give an uninterrupted flow of operation.
A further object and advantage is to angulate the saw head by means of a servo motor coupled to a ninety degree worm gear drive. This configuration, which has no exposed moving parts, is not subject to fouling by saw dust. The servo motor and worm gear drive combination also, as before performs multiple functions as it sets the angle of cut as well as locks the cut head in position to insure an accurate cut. The rotational play caused by clearance between the gear teeth is compensated for in the motion control software.
Another object is to construct a saw that is a self contained unit, capable of being transported easily and requiring no excessive setup procedure. This is accomplished by providing a rigid self supporting frame to which all the saw components are attached. The saw requires no leveling, calibrating nor does it need to be bolted to a concrete base,
A still further object pertains to safety. All of the saws moving parts are housed within a heavy gauge steel cabinet whose door is equipped with an electronic safety lock and all the electrical components are housed within heavy gauge steel, dustproof enclosures.